1902.] Properties. of Saliva of " Non- poisonous" Colubrines. 447 



parotid gland is a generally accepted fact. That various gradations 

 exist between an ordinary serpent's tooth and the " perforated" tooth 

 of the venomous snakes is equally well known. If then we can show 

 that the parotid secretion of the " harmless " Colubrines is in any 

 degree poisonous, and if, moreover, in a series of such harmless 

 Colubrines we can find degrees of virulence, we shall, we think, have 

 done something towards placing the venom apparatus of the Thanato- 

 phidia at one extreme of a natural series in harmony with other facts 

 of evolution. At one end of this series we shall have a snake like the 

 Eat-snake (Zamenis mucosus) with a parotid secretion that is small in 

 amount and only slightly toxic, and with no special means of inject- 

 ing its secretion; at the other end of the series we shall have the 

 Cobra, whose abundant parotid secretion is of lethal virulence and 

 can be powerfully injected by a specialised fang. 



We admit that certain of the links in this series have already been 

 discovered and established, but we do not think that their full 

 evolutional value has yet been assigned to them. 



For instance, Mr. Boulenger, in his ' Catalogue of Snakes,' says of 

 the three Colubrine sub-families Homalopsince, Dipsadomorphince, and 

 Elachistodonfddce, that constitute his section of Opisthoglypha, " most, 

 if not all, of the snakes of this division are poisonous to a slight 

 degree, paralysing their prey before deglutition." 



Again, Mr. G. S. West,* though he apparently speaks with some 

 reserve as to the toxicity of the Opisthoglypha in general, accepts the 

 fact that "the bite of Dryophis and other Opisthoglyphous snakes has 

 been proved by several observers to be fatal to small animals." 



MM. Phisalix and Bertrand,f experimenting with two European 

 species of Tropidonotus, a genus of Aglyphous or " harmless " Colubrines, 

 discovered that the secretion of the salivary glands was fatal to 

 guinea-pigs. 



Earlier still, Mr. J. J. QuelchJ recorded of two American Colubrines 

 — one an Opisthoglyphous or " suspicious " species (Erythrolamprus 

 cesculapii), the other an Aglyphous or " harmless " species (Xenodon 

 sevems) — that their bite could produce enduring and painful inflamma- 

 tion in man. 



In seeking for ourselves some independent evidence for the popular 

 belief that " all snakes are poison," we began with the Opisthoglyphous 

 species Cerberus rhynchops, Dipsas Forstenii, Dryophis mycterizans, and 

 Chrysopelea ornata, all of which have parotid glands of some size and 

 have some of the posterior maxillary teeth enlarged and grooved. 



We used white mice and white rats, and we injected subcutaneously 

 the liquid from the (perfectly fresh) crushed parotid gland, and the 



* 1 Proceedings of the Zoological Society for 1895,' p. 813. 

 f ' Comptes Kenchis,' vol. 118, 1891, pp. 76-79. 

 X 'Zoologist,' 1893, pp. 30, 31. 



